1. Field of the Invention
The invention relates to a work pallet changer, and in particular to a manually operated work pallet changer system.
2. Background of the Invention
In machine shops using large, expensive automatic machine tools, such as the Vertical Machining Center, the Horizontal Machine Center, and Drilling and Tapping machines, it is desirable to keep the machine tool busy in order to make it an effective and efficient investment. Many machine shops have adopted the use of work pallet changers also known as pallet indexers. The use of a pallet indexer permits a machine tool operator to assemble the work on portable pallets and to efficiently move the work to and from a machine tool work table by transferring assembled work pallets. This procedure avoids unnecessary downtime otherwise required to setup and teardown the work directly on the work table.
Using such an indexer, a new work pallet is setup off line while the machining proceeds on a previously assembled work pallet. The indexer is then used to quickly remove a pallet and its completed work from the machine tool and to replace it with the newly setup work pallet. The machine tool is inoperative only during the short time required to exchange the work pallets. In this way the machine tool is kept busy, and the owner's investment is maximized.
A variety of devices and methods have been proposed for this purpose. Among these devices are a class of pallet indexers which operate on a shuttle or side-by-side principle, as for example the pallet changer illustrated in U.S. Pat. No. 5,156,254. Another popular class of pallet indexers uses a rotary or carousel principle, as illustrated for example in U.S. Pat. No. 5,018,617.
Some indexers are manually operated, while many others are semi-automatic or even fully automatic in operation. Though these pallet indexers achieve the goal of keeping the machine tool busy, they tend to suffer from two major problems which undermine the goal of maximizing the owner's investment.
The first problem relates to the manner in which the side-to-side indexers interfere with a machine tool operator's ability to physically monitor the work in progress. These shuttle-type indexers often include a portion connecting two side units. That portion extends outwardly from the machine tool near a position at which the machine tool operator must stand in order to effectively observe and monitor the machining operation. In such cases, the machine tool operator must lean across this connecting portion in order to observe and listen to the work as it proceeds. Though it is possible for the machinist to work in this manner, the leaning-across increases fatigue and interferes with both his efficiency and his ability to use skills effectively to insure the machining is properly carried out. This shortcoming tends to be present in both the manually operated and the automatic indexers of the side-to-side configuration.
The second common problem relates to the complexity of the automatic and the semi-automatic indexers, and even many of the manually operated devices. These indexers are expensive to purchase and are often costly to maintain. What is gained in efficient machine shop operation, is lost in an increased, and often hidden cost for indexer maintenance and repair. As a result, the apparent savings are somewhat illusory, particularly in the smaller and mid-sized machine shop.
It would be desirable to provide a work pallet changer that is relatively inexpensive to purchase, that provides an increase in productivity by being easy to operate, that is configured to permit the machine tool operator to monitor the work without undue fatigue, and which presents the shop owner with few hidden costs related to upkeep.